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Background: Dedifferentiated liposarcoma (DDLPS) is a rare mesenchymal cancer originating from the adipose tissue, with poor survival rates for most patients, highlighting the critical need for novel treatment options. Case description: This report examines the efficacy and safety of sequential pre-treatment with the marine-derived alkaloid trabectedin followed by checkpoint inhibition using the anti-PD-1 antibody nivolumab in a 63-year-old male patient with unresectable retroperitoneal DDLPS. Treatment was initiated at the time of the seventh relapse as part of the NitraSarc phase 2 multicenter trial for inoperable soft tissue sarcoma conducted by the German Interdisciplinary Sarcoma Group (GISG-15, NCT03590210). The patient demonstrated an immediate tumor response, and in combination with minor surgery, achieved R0 resection status, which was subsequently maintained without the need for further therapy for the past 52 months. Correlative molecular analyses revealed a sustained DNA damage repair machinery and downregulation of PD-1 protein expression in post-treatment tumor samples. Conclusion: This report provides exemplary insight on the feasibility and efficacy of sequential pre-treatment with trabectedin as a priming strategy for PD-1 inhibition in advanced DDLPS. Full trial results from NitraSarc are pending for publication. [ABSTRACT FROM AUTHOR]

Liposarcoma is the most prevalent sarcoma in adults representing 20% of all sarcomas with well-differentiated/dedifferentiated among the most common subtypes represented. Despite multimodality treatment approaches, there has not been any appreciable change in survival benefit in the past 10 years. The future of targeted therapy for WD/DDLPS is promising with the intention to spare multi-visceral removal due to radical surgical resection. Therefore, there is a need to expand upon the molecular landscape of WDLPS and DDLPS which can help identify potential therapeutic targets for the treatment of this disease. Targeted transcriptome analysis using the NanoString tumor signaling 360 panel revealed a dysregulation in glucose metabolism and HIF1 signaling pathways in both WDLPS and DDLPS when compared to normal fat controls. WDLPS, however, demonstrated upregulation of HIF-1A and TGF-β when compared to DDLPS by targeted transcriptome analysis and orthogonal validation by RT-qPCR suggesting activation of EMT pathway in WDLPS when compared to DDLPS. Our findings implicate a putative role for dysregulation in glucose metabolism, TGF-β and HIF1 signaling in the pathogenesis of both WD/DDLPS suggesting a possible proinflammatory tumor environment within WDLPS and subsequent activation of the TGF-β signaling pathway. [ABSTRACT FROM AUTHOR]

Abstract This correspondence addresses the article published by Nie et al. titled “Primary extraskeletal osteosarcoma of sigmoid mesocolon: a case report and a review of the literature”. Their report highlighted an extremely rare case of extraskeletal osteosarcoma (EO) in the sigmoid mesocolon that was diagnosed through imaging and histopathological findings. Diagnosing EO has certain challenges; one of them being the lack of characteristic image findings of EO and the other being the lack of appropriate immunohistochemical (IHC) markers in the histopathological findings. Recently, special AT-rich sequence-binding protein 2 (SATB2) has been proposed as an IHC marker for osteoblastic differentiation; however, it has low specificity. Some cases of EO may show findings such as mouse double minute protein 2 expression and deletion of histone H3 lysine 27 trimethylation (H3K27me3), which are similar to those of other soft tissue sarcomas. Therefore, it is essential to consider other soft tissue sarcomas, especially dedifferentiated liposarcoma, before the accurate diagnosis of EO.

Abstract Background Dedifferentiated liposarcoma of the extremities (DDL-E) is rare in comparison to that of the retroperitoneum. Its clinical features and surgical principle for resection margins at the dedifferentiated and the well-differentiated components are yet to be elucidated. Methods This retrospective multi-center study examined patients diagnosed with DDL-E from August 2004 to May 2023 at 5 sarcoma centers. Clinical features, oncologic outcomes, and prognostic factors were analyzed. Results A total of 107 patients were reviewed. The 5-year local recurrence free survival (LRFS), metastasis-free survival (MFS) and disease specific survival (DSS) were 84.7%, 78.6%, and 87.8%, respectively. Other primary malignancies and extrapulmonary metastasis were observed in 27 and 4 patients, respectively. The independent risk factor for local recurrence was R1/2 margin at the dedifferentiated component of the tumor. Metastasis was associated with tumor size in univariate analysis. The independent risk factor for DSS was tumor grade. Previous unplanned excision, de novo presentation, tumor depth, absence of the well-differentiated component, infiltrative border, R1/2 margin at the well-differentiated component were not associated with oncologic outcomes. Conclusions This is the largest study examining DDL-E to-date. Localized DDL-E has low potential for metastasis and carries an excellent prognosis. Other primary malignancy and extrapulmonary metastasis are more frequent in DDL-E, thus close monitoring of other sites during follow-up is recommended. While wide resection margin is the standard surgical approach for DDL-E, further investigation into moderated wide resection margin at the well-differentiated component is warranted.

Dedifferentiated liposarcoma is a malignant lipomatous tumor that rarely occurs in the gastrointestinal tract, including the ileocecal region. In this case, computed tomography and magnetic resonance imaging showed no fatty mass located in the mesenteric or submucosal lesion, and positron emission tomography–computed tomography showed a high maximum standardized uptake value, collectively indicating the gastrointestinal stroma tumor and lymphoma. The pathological findings resemble leiomyosarcoma; the immunohistochemistry findings including mouse double minute 2 homolog and cyclin D-dependent kinase-4 and amplification of mouse double minute 2 homolog in fluorescence in situ hybridization just favored the diagnosis of dedifferentiated liposarcoma with leiomyosarcoma phenotype and not leiomyosarcoma. Recently, a new inhibitor for mouse double minute 2 homolog and cyclin D-dependent kinase-4 has been developed, and clinical trials for dedifferentiated liposarcoma are currently ongoing. This could change the treatment strategy drastically compared with other soft tissue sarcomas. Hence, a correct diagnosis of dedifferentiated liposarcoma is required. [ABSTRACT FROM AUTHOR]

This correspondence addresses the article published by Nie et al. titled "Primary extraskeletal osteosarcoma of sigmoid mesocolon: a case report and a review of the literature". Their report highlighted an extremely rare case of extraskeletal osteosarcoma (EO) in the sigmoid mesocolon that was diagnosed through imaging and histopathological findings. Diagnosing EO has certain challenges; one of them being the lack of characteristic image findings of EO and the other being the lack of appropriate immunohistochemical (IHC) markers in the histopathological findings. Recently, special AT-rich sequence-binding protein 2 (SATB2) has been proposed as an IHC marker for osteoblastic differentiation; however, it has low specificity. Some cases of EO may show findings such as mouse double minute protein 2 expression and deletion of histone H3 lysine 27 trimethylation (H3K27me3), which are similar to those of other soft tissue sarcomas. Therefore, it is essential to consider other soft tissue sarcomas, especially dedifferentiated liposarcoma, before the accurate diagnosis of EO. [ABSTRACT FROM AUTHOR]

Primary intracranial sarcomas constitute a rare group of tumors, with the most common types described in the literature being chondrosarcoma and fibrosarcoma. Dedifferentiated liposarcoma (DDLS) is a high‐grade sarcoma that sometimes metastasizes to the brain. However, a primary intracranial DDLS is exceedingly rare. A 45‐year‐old patient from the Middle East came to India for treatment. His magnetic resonance imaging (MRI) scans revealed a space‐occupying lesion at the level of the lateral ventricle T2/fluid attenuated inversion recovery hyperintensity with peripheral edema. A T1 perfusion map showed high relative cerebral blood volume values in the peripheral part, suggesting a high‐grade neoplasm. Gross total resection was performed, and histopathology showed a high‐grade tumor composed of sheets of pleomorphic lipoblasts and epithelioid tumor cells arranged in nests and cords. Immunohistochemistry showed diffuse immunopositivity for MDM2, CDK4, and p16, while GFAP and OLIG2 were negative. Fluorescence in situ hybridization showed MDM2 amplification. Final diagnosis of DDLS was rendered. The patient had no systemic lesions elsewhere on positron emission tomography computed tomography scan. [ABSTRACT FROM AUTHOR]

The article discusses the novel role of MDM2 in the diagnosis and treatment of dedifferentiated liposarcoma, a subtype of liposarcoma that often occurs in the retroperitoneum. It highlights the importance of MRI, histopathology, and treatment strategies in managing this condition. The study emphasizes the significance of MDM2 and CDK4 in immunohistochemistry and fluorescence in situ hybridization for accurate diagnosis and potential therapeutic targets. The research provides insights into the clinical features, diagnostic challenges, and treatment options for dedifferentiated liposarcoma, contributing to advancements in the field of oncology. [Extracted from the article]

Background: Pulmonary nodules in patients with soft tissue sarcomas are likely pulmonary metastases, whereas synchronous primary pulmonary sarcomas are rare. Without surgery, determining whether a solitary pulmonary nodule is a primary or metastatic nodule is difficult. Herein, we report a rare case of a primary pulmonary sarcoma that presented synchronously with a primary dedifferentiated liposarcoma. Case presentation: A 77-year-old man presented to another hospital with left inguinal swelling and a suspected recurrent inguinal hernia. Computed tomography revealed a left inguinal mass and pure-solid nodule in the left lung and the patient was referred to our hospital for detailed examination and treatment. The inguinal mass was pathologically diagnosed as a dedifferentiated liposarcoma using needle biopsy, whereas bronchoscopic biopsy revealed histological findings suggestive of a sarcoma; however, the primary site could not be determined. Positron emission tomography–computed tomography revealed no high-accumulation lesions except for the two sarcomas. We decided to perform surgery on both sarcomas for diagnostic and curative purposes. The surgical specimens showed that the two sarcomas were different. Based on the immunohistochemical staining findings of MDM2, a left inguinal dedifferentiated liposarcoma and primary pulmonary unclassified sarcoma were diagnosed. The patient displayed no evidence of recurrence 1 year after surgery. Conclusions: We encountered a rare case of synchronous multiple primary sarcomas, one presenting in the lung and the other in the soft tissue. Surgery was required to achieve a definitive diagnosis for the patient, who achieved disease-free survival at 1 year. This case suggests that proactive resection of pulmonary nodules in patients with soft tissue sarcomas may be feasible as a diagnostic treatment if complete resection is achieved. [ABSTRACT FROM AUTHOR]

Background: Dedifferentiated liposarcoma of the extremities (DDL-E) is rare in comparison to that of the retroperitoneum. Its clinical features and surgical principle for resection margins at the dedifferentiated and the well-differentiated components are yet to be elucidated. Methods: This retrospective multi-center study examined patients diagnosed with DDL-E from August 2004 to May 2023 at 5 sarcoma centers. Clinical features, oncologic outcomes, and prognostic factors were analyzed. Results: A total of 107 patients were reviewed. The 5-year local recurrence free survival (LRFS), metastasis-free survival (MFS) and disease specific survival (DSS) were 84.7%, 78.6%, and 87.8%, respectively. Other primary malignancies and extrapulmonary metastasis were observed in 27 and 4 patients, respectively. The independent risk factor for local recurrence was R1/2 margin at the dedifferentiated component of the tumor. Metastasis was associated with tumor size in univariate analysis. The independent risk factor for DSS was tumor grade. Previous unplanned excision, de novo presentation, tumor depth, absence of the well-differentiated component, infiltrative border, R1/2 margin at the well-differentiated component were not associated with oncologic outcomes. Conclusions: This is the largest study examining DDL-E to-date. Localized DDL-E has low potential for metastasis and carries an excellent prognosis. Other primary malignancy and extrapulmonary metastasis are more frequent in DDL-E, thus close monitoring of other sites during follow-up is recommended. While wide resection margin is the standard surgical approach for DDL-E, further investigation into moderated wide resection margin at the well-differentiated component is warranted. [ABSTRACT FROM AUTHOR]

Simple Summary: Atypical spindle cell/pleomorphic lipomatous tumor (ASCPLT) is a novel entity of benign adipocytic neoplasm that can show variable CD34 immunoreactivity, loss of Rb expression, and RB1 gene deletion. Due to the rarity of the disease, ASCPLT remains poorly understood. This review aims to provide a comprehensive reference, offer valuable insights into the clinicopathological characteristics and pathogenesis, and discuss the differential diagnosis of ASCPLT. Atypical spindle cell/pleomorphic lipomatous tumor (ASCPLT) is a rare and recently described adipocytic neoplasm that primarily occurs in the subcutis of the limbs and limb girdles, particularly of middle-aged adults. It has locally recurrent potential if incompletely excised but no risk for distant metastasis. ASCPLT is histologically similar to spindle cell/pleomorphic lipoma and atypical lipomatous tumor and shows a mixture of atypical spindle cells, adipocytes, lipoblasts, floret-like multinucleated giant cells, and/or pleomorphic cells. It has been recently recognized that ASCPLT can undergo sarcomatous transformation. However, the biological significance of morphological sarcomatous transformation in ASCPLT remains uncertain. Immunohistochemically, the tumor cells show variable expression of CD34, S-100 protein, and desmin. Loss of nuclear Rb expression is observed in the majority of cases. ASCPLT lacks MDM2 gene amplification but can show RB1 gene deletion in a significant subset of cases. Complete surgical excision is the treatment of choice. This review provides an overview of the current knowledge on the clinicoradiological features, pathogenesis, histopathology, and treatment of ASCPLT. In addition, we will discuss the differential diagnosis of this new entity. [ABSTRACT FROM AUTHOR]

BackgroundDedifferentiated liposarcoma (DDLPS) is a rare mesenchymal cancer originating from the adipose tissue, with poor survival rates for most patients, highlighting the critical need for novel treatment options.Case descriptionThis report examines the efficacy and safety of sequential pre-treatment with the marine-derived alkaloid trabectedin followed by checkpoint inhibition using the anti-PD-1 antibody nivolumab in a 63-year-old male patient with unresectable retroperitoneal DDLPS. Treatment was initiated at the time of the seventh relapse as part of the NitraSarc phase 2 multicenter trial for inoperable soft tissue sarcoma conducted by the German Interdisciplinary Sarcoma Group (GISG-15, NCT03590210). The patient demonstrated an immediate tumor response, and in combination with minor surgery, achieved R0 resection status, which was subsequently maintained without the need for further therapy for the past 52 months. Correlative molecular analyses revealed a sustained DNA damage repair machinery and downregulation of PD-1 protein expression in post-treatment tumor samples.ConclusionThis report provides exemplary insight on the feasibility and efficacy of sequential pre-treatment with trabectedin as a priming strategy for PD-1 inhibition in advanced DDLPS. Full trial results from NitraSarc are pending for publication.

The neurotrophic tyrosine kinase receptor (NTRK) gene family is of rising importance as their fusions are oncogenic, and specific target drugs are available to inhibit the chimera proteins. Pan-TRK antibody, which shows the overexpression of the NTRK1-2-3 genes, is a useful tool to detect tumors with or without NTRK gene alterations, due to high negative predictive value. Though it is well known that pan-TRK immunopositivity is usually not connected to NTRK fusion, the role of other possible genetic alterations is under-researched. In our previous work, we found 3 NTRK1 amplified cases out of 6 cases with recurrent NTRK1 tyrosine kinase domain mutation pair, so we extended our investigation to a larger series to estimate amplification frequency. Pan-TRK immunopositivity was seen in 76 of the 132 dedifferentiated liposarcomas cases, followed by NTRK1-2-3 break-apart FISH tests in 76 pan-TRK positive cases to detect oncogenic fusions or other copy number alterations of these genes. None of the pan-TRK immunopositive dedifferentiated liposarcomas showed absolutely certain sign of fusion, however, 18 (28%) cases showed amplification of one of the genes, 13 had polysomy, 34 were normal, 11 were not evaluable. The extent of pan-TRK immunoreaction showed a positive correlation (p = 0.002) with the NTRK status found by FISH. Analyzing publicly available data from large series of 265 liposarcoma samples consisting of both well-differentiated and dedifferentiated liposarcoma case, 23 (8.6%) cases showed a mutual exclusive amplification of the NTRK genomic loci in a non-preselected, independent patient population indicating that our findings are presented in other cohorts. Our results underline the so far not revealed frequent occurrence of NTRK amplifications which might be important in the TRK inhibition therapy.

Dedifferentiated liposarcoma (DDLPS) is a non-lipogenic sarcoma, generally arising from well-differentiated liposarcoma (WDLPS), although it can develop de novo. DDLPS tumors rarely trans-differentiate into non-adipose mesenchymal tissues; however, the latter lack notable variety and mostly show striated muscle or osteogenic/chondrogenic differentiation. Here, we report a case of DDLPS that contained numerous atypical vessels. A man in his sixties presented with a large tumor in his right thigh, and the tumor was surgically resected. Microscopically, most of the tumor was WDLPS, but a minor portion showed DDLPS, consisting of high-grade spindle cells. Remarkably, the DDLPS contained vessels of various sizes with atypical cytoarchitecture, including vessels with seemingly muscular layers. Immunohistochemically, the atypical cells within the vascular wall expressed aSMA, consistent with smooth muscle cells or pericytes, whereas surrounding high-grade spindle cells only focally expressed it, and these aSMA-positive cells within the vessels exhibited MDM2 amplification by immuno-fluorescence in situ hybridization. Our results demonstrate that DDLPS can trans-differentiate into smooth muscle cells of various-sized accompanying vessels, which may support their survival and proliferation. [ABSTRACT FROM AUTHOR]

Liposarcoma is the most prevalent sarcoma in adults representing 20% of all sarcomas with well-differentiated/dedifferentiated among the most common subtypes represented. Despite multimodality treatment approaches, there has not been any appreciable change in survival benefit in the past 10 years. The future of targeted therapy for WD/DDLPS is promising with the intention to spare multi-visceral removal due to radical surgical resection. Therefore, there is a need to expand upon the molecular landscape of WDLPS and DDLPS which can help identify potential therapeutic targets for the treatment of this disease. Targeted transcriptome analysis using the NanoString tumor signaling 360 panel revealed a dysregulation in glucose metabolism and HIF1 signaling pathways in both WDLPS and DDLPS when compared to normal fat controls. WDLPS, however, demonstrated upregulation of HIF-1A and TGF-β when compared to DDLPS by targeted transcriptome analysis and orthogonal validation by RT-qPCR suggesting activation of EMT pathway in WDLPS when compared to DDLPS. Our findings implicate a putative role for dysregulation in glucose metabolism, TGF-β and HIF1 signaling in the pathogenesis of both WD/DDLPS suggesting a possible proinflammatory tumor environment within WDLPS and subsequent activation of the TGF-β signaling pathway.

BackgroundLiposarcoma (LPS) is a kind of malignancy of soft tissue usually found in the retroperitoneal, limb, or neck region, and some may be detected with delayed symptoms (pain or palpable mass), and less frequently occurs in organs of the digestive system. In contrast, Dedifferentiated liposarcoma (DDLPS) is a common histological subtype of LPS. The present study reported a case of dedifferentiated liposarcoma originating in the gallbladder. Differentiated liposarcoma originating from the gallbladder is rarely reported.Case descriptionA 64-year-old female patient presented to our hospital with a painless abdominal mass. Abdominal computed tomography (CT) showed that the gallbladder had lost its normal shape, and a 9.1 cm × 7.1 cm × 12.1 cm mass was seen in the area of the gallbladder fossa and the right upper abdomen below it, which had an irregular morphology, inhomogeneous density, and nodular calcification, with marked inhomogeneous enhancement on enhancement scan. Preoperative tumor markers and liver function indicators were not abnormal. With suspicion of a giant malignant tumor of the gallbladder, she underwent a cholecystectomy combined with abdominal mass resection. After surgery, the tumor and gallbladder, were completely resected, and postoperative pathological results confirmed the diagnosis of dedifferentiated liposarcoma deriving from gallbladder. After surgery, the patient and his family refused to continue treatment. After 15 months follow-up, the patient remains asymptomatic and does not show any signs of recurrence. And she is now under continued follow - up.ConclusionsTreatment of dedifferentiated liposarcoma is still at exploratory stage, and a lack of clinical evidence for this condition might hinder access to clinical trials and studies. Currently, the treatment of choice for dedifferentiated liposarcoma remains radical resection. In the available clinical studies, there are no robust data to support clinical use of neoadjuvant and adjuvant radiochemotherapy. As with other diseases, the use of radiotherapy and chemotherapy before and after surgery may be a potential future treatment.

Dedifferentiated liposarcoma is a malignant lipomatous tumor that rarely occurs in the gastrointestinal tract, including the ileocecal region. In this case, computed tomography and magnetic resonance imaging showed no fatty mass located in the mesenteric or submucosal lesion, and positron emission tomography–computed tomography showed a high maximum standardized uptake value, collectively indicating the gastrointestinal stroma tumor and lymphoma. The pathological findings resemble leiomyosarcoma; the immunohistochemistry findings including mouse double minute 2 homolog and cyclin D-dependent kinase-4 and amplification of mouse double minute 2 homolog in fluorescence in situ hybridization just favored the diagnosis of dedifferentiated liposarcoma with leiomyosarcoma phenotype and not leiomyosarcoma. Recently, a new inhibitor for mouse double minute 2 homolog and cyclin D-dependent kinase-4 has been developed, and clinical trials for dedifferentiated liposarcoma are currently ongoing. This could change the treatment strategy drastically compared with other soft tissue sarcomas. Hence, a correct diagnosis of dedifferentiated liposarcoma is required.

BackgroundAlthough IGF2BP3 has been implicated in tumorigenesis and poor outcomes in multiple cancers, its role in soft-tissue sarcoma (STS) remains unknown. Preliminary data have suggested an association with IGF2BP3 expression among patients with well-differentiated/dedifferentiated liposarcoma (WD/DD LPS), a disease where molecular risk stratification is lacking.MethodsWe examined the survival associations of IGF2BP3 via univariate and multivariate Cox regression in three unique datasets: (1) the Cancer Genome Atlas (TCGA), (2) an in-house gene microarray, and (3) an in-house tissue microarray (TMA). A fourth dataset, representing an independent in-house TMA, was used for validation.ResultsWithin the TCGA dataset, IGF2BP3 expression was a poor prognostic factor uniquely in DD LPS (OS 1.6 vs. 5.0 years, p = 0.009). Within the microarray dataset, IGF2BP3 expression in WD/DD LPS was associated with worse survival (OS 7.7 vs. 21.5 years, p = 0.02). IGF2BP3 protein expression also portended worse survival in WD/DD LPS (OS 3.7 vs. 13.8 years, p < 0.001), which was confirmed in our validation cohort (OS 2.7 vs. 14.9 years, p < 0.001). In the multivariate model, IGF2BP3 was an independent risk factor for OS, (HR 2.55, p = 0.034).ConclusionIGF2BP3 is highly expressed in a subset of WD/DD LPS. Across independent datasets, IGF2BP3 is also a biomarker of disease progression and worse survival.

Tianwen Zhang, Bin Liu Department of Orthopaedic Soft Tissue Surgery, Guangxi Medical University Cancer Hospital, Nanning, 530021, People’s Republic of ChinaCorrespondence: Bin Liu, Email lbstar@gxmu.edu.cnObjective: The study aimed to investigate the significantly different imaging characteristics of musculoskeletal dedifferentiated liposarcoma (DDLP) and well differentiated liposarcoma (WDLP) on MRI, which in turn could guide puncture biopsy.Materials and Methods: This study included 14 patients with DDLP and 16 patients with WDLP, all of whom were confirmed by histopathological examination. The MRI manifestations of these two pathologies were retrospectively reviewed and compared. Furthermore, a step-by-step procedure regarding preoperative puncture biopsy of fatty masses that are suspicious for WD/DD was designed.Results: Fatty signals can be found in almost all WDs, with a greater proportion of non-fatty areas in DD compared to WD, and it is reasonable to consider WD more likely when the non-fatty areas of the tumor are < 25% (p < 0.05), while it is reasonable to consider DD more likely when the non-fatty areas of the tumor are > 50% (p < 0.05), and the MRI signals in DD are more complex, inhomogeneous (p < 0.01), usually showed significant enhancement (p < 0.01), and the margins of the tumor were usually indistinct (p < 0.01); and imaging features such as tumor size, vascularity, necrosis, and peritumoral edema did not serve as distinguishing features between the two (p > 0.05).Conclusion: DD has a greater proportion of non-fatty components, with more complex and inhomogeneous MRI signals, and typically shows significant enhancement, with usually indistinct margins of the tumor, in which the inhomogeneous manifestations are associated with the histological components. The possibility of DD should be considered in fatty tumors with non-fatty areas > 25%, for which puncture biopsy is necessary, while simultaneous puncture of low, moderate, high-signal areas within the non-fatty area could improve the accuracy of preoperative puncture pathology.Keywords: liposarcoma, dedifferentiated liposarcoma, well-differentiated liposarcoma, magnetic resonance imaging, puncture biopsy

Dedifferentiated liposarcoma is a high-grade entity developed from a preexisting or recurrent well-differentiated liposarcoma, and rarely, it may contain divergent differentiation. We presented the case of a 39-year-old woman with retroperitoneal dedifferentiated liposarcoma with heterologous low-grade osteosarcoma, possessing a special pattern of tumoral calcification.

Myxofibrosarcomas (MFS) present as slowly enlarging superficial masses in elderly patients. Even though these tumors fail to exhibit a distinct immunophenotype, diagnosis is straightforward when they present in subcutaneous tissue. Intramuscular MFS, however, are more challenging to diagnose as the differential also includes dedifferentiated liposarcoma with myxoid features. The vast majority of dedifferentiated liposarcomas show MDM2 amplification, whereas limited data exists as to the MDM2 status of MFS. We sought to explore the rate of MDM2 amplification in cases of classic MFS. Our archives were searched for MFS; only subcutaneous well-sampled resections were included. FISH for MDM2 amplification was performed on each tumor. A cohort of myxoid dedifferentiated liposarcoma resections was studied for comparison. Twenty-two MFS arose in patients aged 44 to 85 years. All tumors contained an infiltrative population of atypical cells embedded in a myxoid stroma with curvilinear blood vessels. MDM2 amplification by FISH was identified in 3 (of 22; 14%) tumors. Available follow up on 17 patients (range 1-96 months; median 13 months) revealed 6 patients with local recurrence and 1 with distant metastasis. Of 3 patients with MDM2- amplified MFS, 1 experienced recurrence and died of unrelated causes, while the second was alive without disease 12 months after diagnosis. Even though the rate of MDM2 amplification by FISH in MFS appears to be low, a subset of cases may show this genetic alteration, which pathologists should be aware of to avoid misclassification as myxoid dedifferentiated liposarcomas. Further studies are necessary to determine if amplification status adds prognostic value. [ABSTRACT FROM AUTHOR]

Objective: Liposarcoma (LPS) is classified into 4 subtypes. As some subtypes have a high recurrence rate, knowing the risk of recurrence before surgery is important. Here, we aimed to investigate the relationship between Hounsfield units (HU) derived from preoperative computed tomography (CT) and the prognosis of patients undergoing surgery. Materials and Methods: We included 32 patients who underwent surgery for LPS between 2014 and 2022. Preoperative plain CT images were collected, and the HU value of each LPS was measured. The association between 2 HU categories (HU < cut-off vs. = cut-off) and clinical variables was assessed. The optimal cut-off value was determined using statistical methods. We used the Kaplan-Meier method to determine the differences between the 2 HU categories at 2 endpoints: recurrence-free survival (RFS) and overall survival (OS). Results: The dedifferentiated subtype showed significantly higher HU values than the other subtypes (P < .001). The optimal cut-off value for HU was 20. HU < 20 was associated with young age, low-performance status, low Charlson Comorbidity Index, and well-differentiated pathology. The Kaplan-Meier curves demonstrated that RFS and OS were significantly shorter in patients with HU = 20 than in those with HU < 20 (P = .007 and .04, respectively). However, when stratified based on subtype, no significant differences were observed between dedifferentiated and other subtypes. Conclusion: HU = 20 on preoperative CT was associated with poor prognosis in LPS patients. Our findings suggest that preoperative CT-derived HU values may serve as useful predictors of prognosis. [ABSTRACT FROM AUTHOR]

Purpose: Liposarcoma is a mesenchymal neoplasm and comprise 20%–30% of all soft tissue sarcomas, accounting for 1% of all malignancies. This study documented the clinical manifestation and oncological outcomes of dedifferentiated liposarcoma (DDLPS). Materials and Methods: Eleven patients were diagnosed and treated for DDLPS between January 2013 and December 2020. The age, gender, symptom onset, tumor location, magnetic resonance images, surgical margin, and pathologic diagnosis of the identified cohort were reviewed. The time to local recurrence or metastasis, follow-up duration, and the patients’ final status were analyzed. Results: The patients comprised seven male and four female patients with a mean age of 59 years (43–73 years). The tumor location was in the thigh in five, inguinal in two, upper arm in two, forearm in one, and popliteal in one. The average tumor diameter was 12 cm (3.5–27.0 cm). At the time of diagnosis, one patient was American Joint Committee on Cancer stage IB, two were II, four were IIIA, and four were IIIB. Local recurrence occurred in four, and distant metastasis occurred in five. The five-year overall survival of patients with DDLPS was 54.5±17.6%, and four died due to disease progression. Conclusion: Primary DDLPS in the extremities is a subtype of liposarcoma with a poorer prognosis than well-differentiated liposarcoma and myxoid liposarcoma. [ABSTRACT FROM AUTHOR]

Background: Dedifferentiated liposarcoma is a formidable sarcoma subtype due to its high local recurrence rate and resistance to medical treatment. While 2D cell cultures are still commonly used, 3D cell culture systems have emerged as a promising alternative, particularly scaffold-based techniques that enable the creation of 3D models with more accurate cell-stroma interactions. Objective: To investigate how 3D structures with or without the scaffold existence would affect liposarcoma cell lines growth morphologically and biologically. Methods: Lipo246 and Lipo863 cell lines were cultured in 3D using four different methods; Matrigel® ECMscaffold method, Collagen ECMscaffold method, ULA plate method and Hanging drop method, in addition to conventional 2D cell culture methods. All samples were processed for histopathological analysis (HE, IHC and DNAscope™), Western blot, and qPCR; moreover, 3D collagen-based models were treatedwith different doses of SAR405838, a well-known inhibitor of MDM2, and cell viability was assessed in comparison to 2D model drug response. Results: Regarding morphology, cell lines behaved differently comparing the scaffold-based and scaffold-free methods. Lipo863 formed spheroids in Matrigel® but not in collagen, while Lipo246 did not form spheroids in either collagen or Matrigel®. On the other hand, both cell lines formed spheroids using scaffold-free methods. All samples retained liposarcoma characteristic, such as high level of MDM2 protein expression and MDM2 DNA amplification after being cultivated in 3D. 3D collagen samples showed higher cell viability after SAR40538 treatment than 2D models, while cells sensitive to the drug died by apoptosis or necrosis. Conclusion: Our results prompt us to extend our investigation by applying our 3D models to further oncological relevant applications, which may help address unresolved questions about dedifferentiated liposarcoma biology. [ABSTRACT FROM AUTHOR]

A 70-year-old man with supraglottic carcinoma underwent computed tomography (CT) for staging purposes. A tumor measuring approximately 7 × 10 cm was found incidentally in the left perirenal space. The tumor showed homogeneous high signal intensity on chemical shift subtraction magnetic resonance imaging (CSS-MRI) suggesting the presence of minimal amounts of fat. Five months later, the tumor had grown to approximately 10 × 12 cm with indistinct margins. CSS-MRI showed high signal intensity in the tumor periphery only. The tumor was resected and the pathological diagnosis was angiosarcoma. Angiosarcomas are malignant endothelial vascular neoplasms that are highly invasive to their surroundings. Here we report a case of primary perirenal angiosarcoma that was difficult to differentiate from a dedifferentiated liposarcoma. On CSS-MRI, high signal intensity within a tumor may be a characteristic feature of primary perirenal angiosarcoma.

Dedifferentiated liposarcoma (DDL), a member of malignant mesenchymal tumors, has a high local recurrence rate and poor prognosis. Pyroptosis, a newly discovered programmed cell death, is tightly connected with the progression and outcome of tumor.

Atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDLPS) is usually a solitary adipocytic tumor. ALT/WDLPS shows no potential for metastasis unless it undergoes dedifferentiation. No case of multiple ALT/WDLPS has been reported in recent years. We present a rare case of multiple recurrent liposarcomas. A 71-year-old man with a history of scrotal ALT/WDLPS at 61 years presented with multiple large tumors spread throughout the body. The patient was bedridden and severely limited in his activities of daily living (ADL) due to multiple large tumors in the trunk and lower extremities. Radiological examination revealed multiple adipocytic tumors, mainly in the soft tissues of the trunk and extremities, with several visceral lesions. Tumors were resected in stages, starting with large tumors directly related to disability. Repeated palliative resections improved the patient’s ADL; he regained ambulation and was discharged 18 months after admission. Twelve surgeries were performed to remove 44 adipocytic tumors from the testis, left chest wall, perigastric area, ileum, left inguinal region, both buttocks, thighs, and lower legs. Histological examination revealed dedifferentiated components in five tumors, while 39 tumors were diagnosed as ALT/WDLPS. At the age of 76 years, the patient developed an unresectable dedifferentiated liposarcoma between the heart and aorta, leading to fatality at 79 years. The patient’s clinical course suggested multiple metastases of ALT/WDLPS of scrotal origin or ALT/WDLPS of multicentric origin. Although multicentric ALT/WDLPS or ALT/WDLPS metastases are rare, they should be considered when multiple large adipocytic tumors are found throughout the body. Despite the presence of numerous large malignant tumors, surgical treatments of the lesions can improve ADL and prolong life if the tumors are of low-grade malignancy.

Purpose: To present a rare case of dedifferentiated liposarcoma of the orbit. Observations: A 61-year-old male complained of left-sided proptosis, diplopia, and limited ocular motility for two years. Biopsy results at that time were suggestive of an atypical lipomatous neoplasm. Ten years later, he presented with increase in size of the mass and worsening of his symptoms. Imaging showed a multi-lobulated mass in the left orbit involving the intraconal, medial, and anterior orbit. Decompression and orbitotomy with biopsy were performed to debulk the mass. Pathology showed a low-grade well-differentiated liposarcoma and the patient was monitored thereafter annually. Eight years later, he complained of persistent proptosis and mass effect from the tumor resulting in ptosis and diplopia and underwent orbital exenteration. Histopathological analysis of the exenterated orbit revealed a focal area of dedifferentiated liposarcoma. Conclusions and importance: Dedifferentiation of an orbital mass can occur as a late complication years after the diagnosis of well-differentiated liposarcoma. Compared to the previously published cases of orbital liposarcoma, this presentation shows a prolonged timeline prior to dedifferentiation (18 years after initial diagnosis). Symptoms of growth or invasive features could indicate dedifferentiation and should warrant a biopsy.

Background: Dedifferentiated liposarcoma is a formidable sarcoma subtype due to its high local recurrence rate and resistance to medical treatment. While 2D cell cultures are still commonly used, 3D cell culture systems have emerged as a promising alternative, particularly scaffold-based techniques that enable the creation of 3D models with more accurate cell-stroma interactions.Objective: To investigate how 3D structures with or without the scaffold existence would affect liposarcoma cell lines growth morphologically and biologically.Methods: Lipo246 and Lipo863 cell lines were cultured in 3D using four different methods; Matrigel® ECM scaffold method, Collagen ECM scaffold method, ULA plate method and Hanging drop method, in addition to conventional 2D cell culture methods. All samples were processed for histopathological analysis (HE, IHC and DNAscope™), Western blot, and qPCR; moreover, 3D collagen-based models were treated with different doses of SAR405838, a well-known inhibitor of MDM2, and cell viability was assessed in comparison to 2D model drug response.Results: Regarding morphology, cell lines behaved differently comparing the scaffold-based and scaffold-free methods. Lipo863 formed spheroids in Matrigel® but not in collagen, while Lipo246 did not form spheroids in either collagen or Matrigel®. On the other hand, both cell lines formed spheroids using scaffold-free methods. All samples retained liposarcoma characteristic, such as high level of MDM2 protein expression and MDM2 DNA amplification after being cultivated in 3D. 3D collagen samples showed higher cell viability after SAR40538 treatment than 2D models, while cells sensitive to the drug died by apoptosis or necrosis.Conclusion: Our results prompt us to extend our investigation by applying our 3D models to further oncological relevant applications, which may help address unresolved questions about dedifferentiated liposarcoma biology.

Simple Summary: Liposarcoma is the most widespread soft-tissue sarcoma in adults. This review summarizes the molecular genetics and epigenetics of the main liposarcoma subtypes and corresponding aberration in signaling forming the basis for targeted therapy selection. In recent years, specific inhibitors of CDK4/6 and MDM2 and VEGFR/FGFR/PDGFR multi-kinase inhibitors have been proposed for the treatment of liposarcoma. Liposarcoma (LPS) is one of the most common adult soft-tissue sarcomas (STS), characterized by a high diversity of histopathological features as well as to a lesser extent by a spectrum of molecular abnormalities. Current targeted therapies for STS do not include a wide range of drugs and surgical resection is the mainstay of treatment for localized disease in all subtypes, while many LPS patients initially present with or ultimately progress to advanced disease that is either unresectable, metastatic or both. The understanding of the molecular characteristics of liposarcoma subtypes is becoming an important option for the detection of new potential targets and development novel, biology-driven therapies for this disease. Innovative therapies have been introduced and they are currently part of preclinical and clinical studies. In this review, we provide an analysis of the molecular genetics of liposarcoma followed by a discussion of the specific epigenetic changes in these malignancies. Then, we summarize the peculiarities of the key signaling cascades involved in the pathogenesis of the disease and possible novel therapeutic approaches based on a better understanding of subtype-specific disease biology. Although heterogeneity in liposarcoma genetics and phenotype as well as the associated development of resistance to therapy make difficult the introduction of novel therapeutic targets into the clinic, recently a number of targeted therapy drugs were proposed for LPS treatment. The most promising results were shown for CDK4/6 and MDM2 inhibitors as well as for the multi-kinase inhibitors anlotinib and sunitinib. [ABSTRACT FROM AUTHOR]

Introduction: Liposarcomas are the most common of all sarcomas. A well-differentiated liposarcoma can transform into a dedifferentiated liposarcoma with myogenic, osteo- or chondrosarcomatous heterologous differentiation. Genomic amplification of MDM2 gene is then characteristic. Treatment usually involves surgical resection to radically remove the tumor. Other treatments such as chemotherapy and radiotherapy may also be used. Case report: A 60-year-old patient was admitted to the hospital for surgical treatment of a left renal mass. The true location of the tumor was discovered only intraoperatively. The lesion was completely removed laparoscopically with preservation of the capsule. Genomic amplification of MDM2 gene was confirmed. One and a half years after surgery, despite the removal of the tumor without the surrounding margin of healthy tissue, the patient remains without recurrence. Conclusion: Dedifferentiated liposarcoma with osteosarcomatous differentiation is a sporadic case and may occur in various locations of the retroperitoneal space, also mimicking a renal tumor. The laparoscopic technique is a safe surgical treatment for tumors of unclear origin. Removal of dedifferentiated liposarcoma with osteosarcomatous differentiation tumor with preservation of the lesion capsule without maintaining a margin of healthy tissue also allows for long-term cure. Precise immunohistochemical and molecular studies may have an impact on the effectiveness of further treatment and the prognosis of the patient. A patient after surgical treatment of liposarcoma requires constant outpatient follow-up for the reason of the high risk of local and distant recurrence. [ABSTRACT FROM AUTHOR]

Liposarcomas are rare, malignant tumors of adipocyte differentiation. Surgery is the main treatment method. We are reporting a rare case of a 65- year- old female patient with a massive dedifferentiated thigh liposarcoma that was growing for 10 years and spread to the retroperitoneum. [ABSTRACT FROM AUTHOR]

Liposarcomas originating in the urinary bladder are extremely rare. Only six cases of bladder liposarcoma have been reported, and all have been described as myxoid liposarcomas. Notably, none of the patients underwent molecular testing. Here, we report a dedifferentiated liposarcoma (DDL) that occurred in the urinary bladder, primarily in a 69-year-old Chinese woman, with infrequent low-grade dedifferentiation. Computed tomography (CT) revealed an ill-defined solid mass in the anterior bladder wall. The patient underwent a partial bladder resection. Histologically, the tumor cells with mild-to-moderate nuclear atypia were arranged in fascicular and storiform patterns, mimicking a low-grade fibroblastic tumor. In addition, scattered small foci of typical lipoma-like welldifferentiated components were identified. Immunohistochemically, the tumor tested positivity for MDM2, CDK4, and p16. Fluorescence in situ hybridization revealed MDM2 gene amplification in the neoplastic cells. Whole-exome sequencing showed that this tumor also harbored CDK4, TSPAN31, and JUN amplification. At the latest follow-up (85 months after surgery), the patient was alive, with no evidence of disease. To the best of our knowledge, this is the first example of a molecularly confirmed primary bladder liposarcoma and the first case of DDL at this site. [ABSTRACT FROM AUTHOR]

Primary liposarcoma of the breast is an uncommon soft tissue malignant tumor, comprising only 0.003% of all malignant breast tumors. The main differential diagnosis of this mass consists of malignant phyllodes tumor and metaplastic breast carcinoma. The objective of this paper is to report a case of dedifferentiated breast liposarcoma, therapeutic approach and outcome. We present a case of a 79-year-old woman complaining of a large mass in her left breast which had increased in size over the last 6 months. Physical examination revealed an enlarged left breast, and a total body CT scan showed a large tumor in contact with the musculature of the anterior thoracic wall, with no metastatic lesions. The histopathology report of a fine needle biopsy described a high-grade sarcoma. The Oncological Tumor Board recommended neoadjuvant radiotherapy sessions and reevaluation by MRI and CT scans. The patient underwent radical mastectomy with latissimus dorsi myo-cutaneous flap reconstruction. The final histopathology diagnosis was a grade 3 dedifferentiated liposarcoma (FNCLCC), with certain response to radiotherapy and positive MDM2, CDK4 markers. The postoperative period was uneventful; 12 months after surgery, the follow-up CT scan showed multiple pulmonary lesions with metastatic characteristics. Liposarcoma is a very rare type of breast cancer, and the most important treatment for breast sarcoma is surgery, the role of axillary lymph node removal, chemotherapy and radiotherapy still being controversial. Considering such cases are scarce and the development of surgical guidelines is difficult, reporting any new case is crucial. [ABSTRACT FROM AUTHOR]

Abstract Background Dedifferentiated liposarcoma (DDLPS) is a rare tumor and generally shows poor prognosis with the lung frequent metastatic site. 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) is used for staging or metastatic evaluation of this disease. We report a case of bilateral lung metastases of DDLPS showing uncommon imaging on FDG-PET/CT with completely different FDG uptake, which made preoperative diagnosis difficult. Case presentation The patient was a male in his 60 s and bilateral lung nodules were noted after proton beam therapy for retroperitoneal DDLPS. FDG-PET/CT showed high FDG uptake in the left S3 15-mm nodule but no uptake in the right S8 10-mm nodule. Thoracoscopic wedge resection for the left nodule was performed, and the pathology revealed metastasis of dedifferentiated liposarcoma. After resection of the left nodule, the right S8 nodule enlarged without FDG uptake. Thoracoscopic right S8 segmentectomy was performed, and metastasis of dedifferentiated liposarcoma was diagnosed. The 2 tumors showed completely different appearances on FDG-PET/CT with similar histopathological findings. Conclusions We encountered a case of multiple pulmonary metastases of DDLPS which did not follow the same imaging appearance on FDG-PET/CT. Appropriate timing of surgical resection for pathological diagnosis should be determined carefully.

Abstract Background Retroperitoneal liposarcoma (RPLPS), a rare tumor, is often treated using surgical procedures as the first choice for treatment. However, there is no consensus on the scope of surgical resection. In addition, the treatment outcomes of conventional radiotherapy and chemotherapy have not been satisfactory, particularly for specific types of LPS, such as dedifferentiated LPS. In this case study, we present a brief review of other cases of RPLPS, highlighting the selection of surgical scope for RPLPS and related adjuvant treatment for advanced RPLPS. Case presentation A case study is reported regarding an extremely rare recurrent and metastatic retroperitoneal dedifferentiated LPS. The primary RPLPS tumor, with a diameter of 20 cm and a weight of 2.5 kg, occupied the whole left abdomen and adhered to the left kidney. A surgical tumor resection combined with a left nephrectomy is performed. During the 6th -month postoperative follow-up examination, we observed the local recurrence of the tumor in the operation area, in addition to multiple metastatic tumors in both lungs. Further, the prescribed 3-month targeted treatment with anlotinib significantly reduced the size of the metastatic pulmonary tumors. However, the recurrent retroperitoneal tumors showed no significant change in size. Eventually, we observed no substantial evidence of tumor progression, with the patient’s condition under control. Conclusion The case demonstrated that the postoperative recurrence of widespread RPLPS required R0 resection to cure the disease, considering targeted therapy for advanced RPLPS control.

Giant paratesticular liposarcoma is a rare presentation of paratesticular tumor. We present a case of the largest paratesticular liposarcoma described to date with a weight of 4,100 g andmeasuring 460 × 210 × 130 mm. It was initiallymistaken as an inguinoscrotal hernia until a contrast-enhanced computed tomography (CECT) scan of the abdomen and pelvis revealed a huge left paratesticular tumor extending from the scrotum to the mid-abdomen. The challenge was to achieve a tumor-free margin orchidectomy due to the poor fat plane of the tumor to the external iliac artery, psoas muscle, descending colon, and anterior abdominal wall. The surgery was started with laparoscopic dissection for the intraabdominal part of tumor from the vital structure, then followed by inguinal radical orchidectomy and inguinal mesh repair. Postoperative histopathological report revealed a paratesticular dedifferentiated liposarcoma with rhabdomyosarcomatous differentiation with clear margin. The patient had good recovery post operation. [ABSTRACT FROM AUTHOR]

Well-differentiated/dedifferentiated liposarcoma (WDLPS/DDLPS) represent a significant number of sarcomas arising within the paratesticular region. DDLPS is notorious for a broad histologic spectrum, but epithelioid morphology is rare. Herein, we describe a unique case of paratesticular DDLPS with prominent epithelioid features and molecular confirmation. The patient is 71-year-old-male who presented with multiple paratesticular masses. Morphologic review of the resection specimen revealed a biphasic adipocytic neoplasm consistent with DDLPS. Additionally, epithelioid foci with acinar and nested architecture and focal keratin expression were noted. These areas raised the possibility of a secondary neoplasm including sex cord stromal tumor, germ cell tumor, and paraganglioma. However, MDM2 immunohistochemistry and FISH showed these areas to express MDM2 and exhibit MDM2 amplification, respectively, confirming that they represented a component of DDLPS. This case further highlights the morphologic diversity of DDLPS as well as the utility of MDM2 studies. [ABSTRACT FROM AUTHOR]

Objective: To analyze the clinical characteristics and diagnosis and treatment of the patient with primary ovarian dedifferentiated liposarcoma (DDLPS), and to improve the clinicians’ understandings of the disease and the levels of diagnosis and treatment. Methods: The clinical data of one patient with primary ovarian DDLPS was colected, and the clinicopathological manifestations, diagnosis, differential diagnosis, treatment, and prognosis were retrospectively analyzed, and the related literatures were reviewed. Results: A 63-year-old female patient was admitted to hospital because of a huge mass in the lower abdomen for half a month. The gynecological ultrasound results showed there was a solid hypoechoic mass, with the size of 17. 0 cm × 9. 3 cm, with an irregular shape and a clear boundary in the middle pelvic cavity after hysterectomy, and there were blood flow signals in the periphery; the bilateral ovaries were not found. The whole abdominal CT results showed there was a huge mixed-density mass in the pelvic cavity, with the lobed lobes and poorly defined boundaries; the size was about 132 mm×86 mm, and the CT value was about 33 HU. The enhancement scaning results showed obvious uneven enhancement of the lesion, obvious enhancement of the edge, and no obvious enhancement of the low-density shadow in the pelvic cavity; the multiple lymph node shadows with the diameter smaller than 6 mm were seen in the pelvic cavity, and the CT enhancement scaning results showed that the lymph nodes were slightly enhancement. The tumor markers had no significant abnormalities. The patient was diagnosis as pelvic mass and the probability of ovarian malignancy was high. After completing all the relevant examinations, the transabdominal bilateral salpingectomy and oophorectomy were performed after general anesthesia. The results of the pathological diagnosis after operation were ovarian DDLPS. No recurrence of the patient was found 10 months after operation. Conclusion: The primary ovarian DDLPS is rare, and the clinical manifestations are not specific; imagological methods are helpful for the diagnosis; radical surgery is the main treatment method; targeted therapy can bring good efficacy for the patients; the disease has high malignancy, poor prognosis, and it is easy to relapse; so long-term follow-up should be performed. [ABSTRACT FROM AUTHOR]

A 51-year-old man with the chief complaint of abdominal pain visited his family doctor. Abdominal ultrasonography showed a large retroperitoneal mass, and the patiant was then referred to our hospital. Computed tomography (CT) scan demonstrated a large tumor (7 × 7 × 10 cm) with nonhomogeneous enhancement within the right retroperitoneum. We performed resection of the tumor under the diagnosis of a malignant soft-tissue tumor. In the microscopic findings, HE staining showed pleomorphic tumor cells with irregular shaped nuclei. In addition, immunohistochemical staining showed that the tumor cells were positive for MDM2 and CDK4. A diagnosis of dedifferentiated liposarcoma was made, and the surgical margin was reported as negative. Adjuvant treatment was not performed, and local recurrence was observed 5 months after surgery. Combination chemotherapy comprising doxorubicin plus ifosfamide was performed, however, tumor response was not seen after two cycles. Eribulin therapy was then performed as a second-line treatment, and complete response was observed after 6 cycles of eribulin therapy. Tumor regrowth has not been seen in the 23 months since the eribulin therapy was started. [ABSTRACT FROM AUTHOR]

A 54-year-old man referred to our hospital for abdominal distension. He had no medical history. On physical examination, he complained lower abdominal distention, and had no spontaneous pain or tenderness. The blood tests showed that CEA and CA19-9 levels were within normal limits. Colonoscopy revealed a submucosal tumor with irregularities and mucosal defects in the descending colon. Computed tomography (CT) showed a 3-cm-diameter mass in the descending colon and ascites. Due to the presence of ascites, laparoscopic examination was performed, which revealed multiple peritoneal seeding of the tumor. Given the presence of peritoneal dissemination, the tumor was determined to be unresectable, and a histological examination was performed from the disseminated nodule. Pathologically, atypical spindle cells were observed and infiltrated into adipose tissue. Additional immunohistochemistry revealed positive expression for Murine double minute 2 (MDM2) and Cyclin-dependent kinase 4 (CDK4), and fluorescence in situ hybridization showed amplification of MDM2. Thus, the tumor was diagnosed with a dedifferentiated liposarcoma of the descending colon. Liposarcoma is a type of soft-tissue sarcoma that arises from soft tissues such as the extremities or retroperitoneum. Here, we report an extremely rare case of a dedifferentiated liposarcoma of the colon. [ABSTRACT FROM AUTHOR]